<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<div class="container">
<div class="row">
<h2>Create your snippet's HTML, CSS and Javascript in the editor tabs</h2>
</div>
</div>
<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<div class="container">
<div class="row">
<div class="col-md-4">
<div class="form_main">
<h4 class="heading"><strong>Quick </strong> Contact <span></span></h4>
<div class="form">
<form action="contact_send_mail.php" method="post" id="contactFrm" name="contactFrm">
<input type="text" required="" placeholder="Please input your Name" value="" name="name" class="txt">
<input type="text" required="" placeholder="Please input your mobile No" value="" name="mob" class="txt">
<input type="text" required="" placeholder="Please input your Email" value="" name="email" class="txt">
<textarea placeholder="Your Message" name="mess" type="text" class="txt_3"></textarea>
<input type="submit" value="submit" name="submit" class="txt2">
</form>
</div>
</div>
</div
</div>
</div>